Paediatrics: Renal calculi

Renal calculi

The incidence of renal calculi varies according to geography and socio-economic conditions around the world. In the UK it affects approximately 1.5/million child population.

Aetiology

Infective

·  Commonest cause in children in UK.

·  Associated with chronic UTI with Proteus—‘staghorn’ calculi.

·  Also UTI with Pseudomonas, Klebsiella, E. coli.

Associated with urinary stasis

Congenital malformations, e.g.:

·  pelviureteric junction obstruction;

·  megaureter.

Metabolic

·  Hypercalciuria: i.e. 24hr urinary Ca >0.1mmol/kg/day or urinary

·  Ca:creatinine ratio >0.74mmol/mmol:

o primary hyperparathyrodism;

o idiopathic infantile hypercalcaemia;

o hypervitaminosis D;

o prolonged immobilization.

·  Cystinuria (autosomal recessive condition): typically radiolucent stones.

·  Oxalosis: primary hyperoxaluria type I (PH1).

·  Uric acid stones:

·  myeloproliferative disorders following medication/chemotherapy

·  for patients with leukaemia, lymphoma;

·  Lesch–Nyhan syndrome.

Clinical features

Most children will present with either gross or microscopic haematuria. They may be otherwise asymptomatic. The classic symptoms of renal colic are uncommon, e.g. intense pain located in the abdomen or in the loins and back. Symptoms and signs of a UTI may also be present. Some child-ren may describe a sensation of ‘having passed gravel’ on micturition.

Investigations

Urine

·  Dipstick analysis.

·  Microscopy (pH, cells, crystals).

·  Culture (exclude infection).

·  Calcium:creatinine ratio; oxalate:creatinine ratio.

·  Amino acid screen.

Blood

·U&E, bicarbonate, creatinine.

·Calcium, phosphate, PTH.

·Liver function tests.

·Uric acid.

Renal tract ultrasound

Other investigations

·AXR:

o radio-opaque stones: calcium/cysteine/infective;

o radiolucent stones: uric acid/xanthine.

·IV pyleogram or CT scan.

·Renal stone analysis: composition.

Treatment

The acute treatment of renal colic secondary to renal stones is based on the provision of adequate analgesia and hydration. Treat any under-lying UTI with antibiotics. If severe renal impairment and urinary tract obstruction is evident refer to the paediatric urology team for considera-tion for extracorporeal shock-wave lithotripsy. Surgery (e.g. percutaneous nephrolithotomy or open surgery) is now seldom indicated. Long-term management is aimed at preventing further obstruction and bouts of renal colic. The simplest and most effective measures to achieve this are to ensure adequate hydration and diuresis to maintain a good urinary flow and dilute urine. Treatment of any underlying urinary tract infection and metabolic disorder is also required.

Primary hyperoxaluria type 1

This is an autosomal recessive condition. Three forms are recognized.

·Infantile form: early nephrocalcinosis and progression to CKD and end-stage renal failure (ESRF/Stage 5 CKD).

·Child/adolescent form: recurrent urolithiasis and progression to ESRF.

·Adult form: urolithiasis only.